mysql数据库—主从同步服务

1、主从同步

1.1、主从同步的两种角色：

主服务器（master）：接受客户端访问连接

从服务器（slave）：自动同步主服务器数据

1.2、主从同步实现的原理：

        主（master）数据服务器启动binlog日志，当binlog日志在备份的时候。从（slave）数据服务器的的I/O线程会自动复制主服务器的binlog日志里面的sql命令到relay_log文件中，从服务器的sql线程会执行relay_log中的sql语句实现与主服务器中的数据一致

1.3、数据库恢复初始化设置

[root@master ~]# systemctl stop mysqld.service 
[root@master ~]# rm -rf /var/lib/mysql/*
[root@master ~]# rm -rf /var/log/mysqld.log 
[root@master ~]# systemctl start mysqld
[root@master ~]# grep "password" /var/log/mysqld.log 
2022-05-16T16:05:03.715052Z 1 [Note] A temporary password is generated for root@localhost: Hm1=3D&y?0lA
[root@master ~]# mysql -uroot -p"Hm1=3D&y?0lA"

2、一主一从服务器架构配置：主从角色的数据库服务器各有一台

2.1、环境配置

master服务器：192.168.4.10

slave服务器：192.168.4.20

两台服务器都安装mysql数据库，并关闭防火墙和selinux

2.2、配置master服务器

1）启用binlog日志文件
[root@master ~]# vim /etc/my.cnf
[mysqld]
server_id=10
log_bin=master10
[root@master ~]# systemctl restart mysqld

2）用户授权，让用户有复制命令权限
[root@master ~]# mysql -uroot -pJY1987...zy2011
mysql> grant replication slave on *.* to repluser@"%" identified by "JY1987...zy2011";
Query OK, 0 rows affected, 1 warning (0.00 sec)

3）日志查看
mysql> show master status;
+-----------------+----------+--------------+------------------+-------------------+
| File            | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-----------------+----------+--------------+------------------+-------------------+
| master10.000001 |      441 |              |                  |                   |
+-----------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

2.2、配置slave服务器

1） 指定server_id，并重启mysqld服务
[root@slave ~]# vim /etc/my.cnf
[mysqld]
server_id=20

2）确保数据一致（如果一致的此步骤可以省略）
3）指定主服务器信息
[root@slave ~]# mysql -uroot -pJY1987...zy2011
mysql> show slave status \G      #不是从服务器显示结果
Empty set (0.00 sec)

mysql> change master to master_host="192.168.4.10",
    -> master_user="repluser",
    -> master_password="JY1987...zy2011",
    -> master_log_file="master10.000001",
    -> master_log_pos=441;
Query OK, 0 rows affected, 2 warnings (0.01 sec)

4）启动slave线程
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

5）查看状态，IO线程和SQL线程必须同时是YES状态
mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Connecting to master
                  Master_Host: 192.168.4.10
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: master10.000001
          Read_Master_Log_Pos: 441
               Relay_Log_File: slave-relay-bin.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: master10.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

3、一主多从服务器架构配置：一台主服务器配置了多台从服务器

3.1、环境配置

master服务器：192.168.4.10

slave服务器：192.168.4.20、192.168.4.30（增加一台从服务器）

延续一主一从的架构，新添加一台从服务器，并安装mysql数据库，并关闭防火墙和selinux

3.2、配置新的slave服务器

1）指定slave_id，并重启mysqld服务
[root@slave2 ~]# vim /etc/my.cnf
[mysqld]
server_id=30
[root@slave2 ~]# systemctl restart mysqld

2）确保和主服务器数据一致性，主做完全备份并拷贝给从。
   --master-data做完全备份数据时，在备份文件里记录使用的日志名和偏移量		
[root@master ~]# mysqldump -uroot -pJY1987...zy2011 --master-data -A > /root/master.sql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
[root@master ~]# scp /root/master.sql 192.168.4.30:/root/

3）从服务器使用备份文件恢复数据。
[root@slave2 ~]# mysql -uroot -pJY1987...zy2011 < master.sql 

3）指定主服务器信息，在备份文件里查看日志名和偏移量
[root@slave2 ~]# grep master10 /root/master.sql 
CHANGE MASTER TO MASTER_LOG_FILE='master10.000001', MASTER_LOG_POS=685;
[root@slave2 ~]# mysql -uroot -pJY1987...zy2011
mysql> change master to master_host="192.168.4.10",
    -> master_user="repluser",
    -> master_password="JY1987...zy2011",
    -> master_log_file="master10.000001",
    -> master_log_pos=685;
Query OK, 0 rows affected, 2 warnings (0.01 sec)

4）启动slave进程，并查看状态（IO线程和SQL线程必须同时是YES状态）
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.4.10
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: master10.000001
          Read_Master_Log_Pos: 685
               Relay_Log_File: slave2-relay-bin.000002
                Relay_Log_Pos: 319
        Relay_Master_Log_File: master10.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

4、主从从服务器架构配置：给一主一从结构中的从服务器也配置从服务器

4.1、环境配置

master服务器：192.168.4.10                      #为slave【1】的主

slave【1】服务器：192.168.4.20               #即为master的从也为slave【2】的主

slave【2】服务器：192.168.4.30               #为slave【1】的从

服务器安装mysql数据库，并关闭防火墙和selinux

4.2、主服务器的配置

[root@master ~]# vim /etc/my.cnf
[mysqld]
server_id=10
log_bin=master10
[root@master ~]# systemctl restart mysqld
[root@master ~]# mysql -uroot -pJY1987...zy2011
mysql> grant replication slave on *.* to slave@"%" identified by "JY1987...zy2011";
Query OK, 0 rows affected, 1 warning (0.00 sec)


mysql> show master status;
+-----------------+----------+--------------+------------------+-------------------+
| File            | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-----------------+----------+--------------+------------------+-------------------+
| master10.000002 |      438 |              |                  |                   |
+-----------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
[root@master ~]# ls /var/lib/mysql/master10.*
/var/lib/mysql/master10.000001  /var/lib/mysql/master10.index

4.3、从服务器【1】的配置：它有两种角色，即为主服务器也为从服务器，因为从服务器也有从服务器所以就要启用级联复制功能。

1）配置主
[root@slave ~]# vim /etc/my.cnf 
[mysqld]
server_id=20
log_bin=zucong20
log_slave_updates  #允许级联复制,当前将自己主服务器的数据拷贝给从服务器
[root@slave ~]# systemctl restart mysqld
[root@slave ~]# mysql -uroot -pJY1987...zy2011
mysql> grant replication slave on *.* to slave2@"%" identified by "JY1987...zy2011";
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> show master status;
+-----------------+----------+--------------+------------------+-------------------+
| File            | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-----------------+----------+--------------+------------------+-------------------+
| zucong20.000001 |      439 |              |                  |                   |
+-----------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

2）配置从
mysql> change master to master_host="192.168.4.10",
    -> master_user="slave",
    -> master_password="JY1987...zy2011",
    -> master_log_file="master10.000002",
    -> master_log_pos=438;
Query OK, 0 rows affected, 2 warnings (0.00 sec)

mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.4.10
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: master10.000002
          Read_Master_Log_Pos: 438
               Relay_Log_File: slave-relay-bin.000002
                Relay_Log_Pos: 319
        Relay_Master_Log_File: master10.000002
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

4.4、从服务器【2】的配置，将这台从服务器配置为服务器【1】的从

1）指定server_id，并重启mysqld服务
[root@slave2 ~]# vim /etc/my.cnf
[mysqld]
server_id=30
[root@slave2 ~]# systemctl restart mysqld

2）指定主服务器的信息
[root@slave2 ~]# mysql -uroot -pJY1987...zy2011
mysql> change master to master_host="192.168.4.20",
    -> master_user="slave2",
    -> master_password="JY1987...zy2011",
    -> master_log_file="zucong20.000001",
    -> master_log_pos=439;
Query OK, 0 rows affected, 2 warnings (0.00 sec)

mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.4.20
                  Master_User: slave2
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: zucong20.000001
          Read_Master_Log_Pos: 439
               Relay_Log_File: slave2-relay-bin.000002
                Relay_Log_Pos: 319
        Relay_Master_Log_File: zucong20.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

5、主主同步：2台数据库服务器，彼此是对方的主服务器，同时还是对方的从服务器 

5.1、环境配置

slave【1】服务器：192.168.4.20

slave【2】服务器：192.168.4.30

服务器安装mysql数据库，并关闭防火墙和selinux

5.2、 slave【1】的配置

[root@slave ~]# vim /etc/my.cnf 
[mysqld]
server_id=20
log_bin=slave20
[root@slave ~]# systemctl restart mysqld
[root@slave ~]# mysql -uroot -pJY1987...zy2011
mysql> grant replication slave on *.* to slave20@"%" identified by "JY1987...zy2011";
Query OK, 0 rows affected, 1 warning (0.01 sec)
mysql> show master status;
+----------------+----------+--------------+------------------+-------------------+
| File           | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+----------------+----------+--------------+------------------+-------------------+
| slave20.000001 |      440 |              |                  |                   |
+----------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

5.3、slave【2】的配置

[root@slave2 ~]# vim /etc/my.cnf
[mysqld]
server_id=30
log_bin=slave30
[root@slave2 ~]# systemctl restart mysqld
[root@slave2 ~]# mysql -uroot -pJY1987...zy2011
mysql> grant replication slave on *.* to slave30@"%" identified by "JY1987...zy2011";
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> show master status;
+----------------+----------+--------------+------------------+-------------------+
| File           | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+----------------+----------+--------------+------------------+-------------------+
| slave30.000001 |      440 |              |                  |                   |
+----------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

1）把自己配置为slave【1】的从服务器，日志名和偏移量要在slave【1】主机查看后填写
mysql> change master to master_host="192.168.4.20",
    -> master_user="slave20",
    -> master_password="JY1987...zy2011",
    -> master_log_file="slave20.000001",
    -> master_log_pos=440;
Query OK, 0 rows affected, 2 warnings (0.00 sec)
mysql> start slave;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.4.20
                  Master_User: slave20
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: slave20.000001
          Read_Master_Log_Pos: 440
               Relay_Log_File: slave2-relay-bin.000004
                Relay_Log_Pos: 318
        Relay_Master_Log_File: slave20.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

 5.4、把slave【1】配置为slave【2】的从服务器，日志名和偏移量要在slave【2】主机查看后填写

mysql> change master to master_host="192.168.4.30",
    -> master_user="slave30",
    -> master_password="JY1987...zy2011",
    -> master_log_file="slave30.000001",
    -> master_log_pos=440;
Query OK, 0 rows affected, 2 warnings (0.00 sec)

mysql> start slave;
Query OK, 0 rows affected (0.00 sec)

mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.4.30
                  Master_User: slave30
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: slave30.000001
          Read_Master_Log_Pos: 440
               Relay_Log_File: slave-relay-bin.000002
                Relay_Log_Pos: 318
        Relay_Master_Log_File: slave30.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes

6、主从同步复制数据工作模式，可以在任意数据库服务器启用半同步服务模式

异步复制：主服务器执行完一次事务后，立即将结果返回给客户端，不关心从服务器是否已经同步数据。

半同步复制：介于异步复制和全同步复制之间，主服务器在执行完一次事务后，等待至少一台从服务器数据完成，才将结果返回给客户端。

6.1、环境配置

master【1】服务器：192.168.4.10

slave【2】服务器：192.168.4.30

服务器安装mysql数据库，并关闭防火墙和selinux

6.2、方法一：命令行设置，不用重启服务马上生效

1）安装模块 
mysql> install plugin rpl_semi_sync_master soname "semisync_master.so";      #master模块
Query OK, 0 rows affected (0.00 sec)

mysql> install plugin rpl_semi_sync_slave soname "semisync_slave.so";        #slave模块
Query OK, 0 rows affected (0.00 sec)

2）查看模块
mysql> select plugin_name,plugin_status from information_schema.plugins where plugin_name like "%semi%";
+----------------------+---------------+
| plugin_name          | plugin_status |
+----------------------+---------------+
| rpl_semi_sync_master | ACTIVE        |
| rpl_semi_sync_slave  | ACTIVE        |
+----------------------+---------------+
2 rows in set (0.00 sec)

3）启动模块
mysql> set global rpl_semi_sync_master_enabled=1;    #主模块
Query OK, 0 rows affected (0.00 sec)


mysql> set global rpl_semi_sync_slave_enabled=1;     #从模块
Query OK, 0 rows affected (0.00 sec)

4）查看模块是否启动
mysql> show variables like "rpl_semi_sync_%_enabled";
+------------------------------+-------+
| Variable_name                | Value |
+------------------------------+-------+
| rpl_semi_sync_master_enabled | ON    |
| rpl_semi_sync_slave_enabled  | ON    |
+------------------------------+-------+
2 rows in set (0.00 sec)

6.2、永久配置，编辑主配置文件

[root@master ~]# vim /etc/my.cnf
[mysqld]
#安装模块
plugin-load="rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so"
#启用模块
rpl_semi_sync_slave_enabled=1
rpl_semi_sync_master_enabled=1

[root@master ~]# systemctl restart mysqld
[root@master ~]# mysql -uroot -pJY1987...zy2011
mysql> show variables like "rpl_semi_sync_%_enabled";
+------------------------------+-------+
| Variable_name                | Value |
+------------------------------+-------+
| rpl_semi_sync_master_enabled | ON    |
| rpl_semi_sync_slave_enabled  | ON    |
+------------------------------+-------+
2 rows in set (0.00 sec)